Method to Sterilize a Packaging Machine

ABSTRACT

A method to sterilize a packaging machine provided with a feed circuit ( 100 ), includes a first feed line configured to feed a first flow of product, a second feed line configured to feed a second flow of sterilizing solution, and a third feed line configured to feed a third flow of gaseous fluid, as well as a forming and filling station equipped with a delivery member fluidically connected to the feed lines and around which it is provided to form a tubular wrapping of heat-sealable film.

FIELD OF THE INVENTION

Embodiments described here concern a method to sterilize a packaging machine, in particular a method which comprises sterilizing a feed circuit of a packaging machine.

BACKGROUND OF THE INVENTION

Aseptic packaging machines are known in the state of the art, for forming and filling wrappings, in particular of the stick-pack or tubular type, with products to be kept in a sterile environment, for example, food products, in particular liquids.

The wrappings are made by winding one or more sheets of film around a feed member, typically a nozzle, in correspondence with a forming and heat-sealing station.

The material that forms the wrapping has to be sterilized before it comes into contact with the product, in order to prevent the proliferation of microorganisms, molds, etc. inside the wrapping.

To achieve this, it is known to sterilize the films by immersing them in sterilization zones provided with appropriate tanks containing liquid sterilizing means such as hydrogen peroxide solutions.

According to other solutions known in the state of the art, it is also known to sterilize the film during the formation and filling of the wrapping around the member that feeds the product. Solutions of this type are described, for example, in prior patent documents U.S. Pat. No. 5,335,479 and EP 3.643.630.

In aseptic packaging machines of this type, it is fundamental that the parts of the machine that come into contact with the product or with the wrapping disposed around the feed member intended to enclose the product are not exposed to contamination after being sterilized, but before the step of filling the wrapping with the product. It is obvious that this is a crucial and very delicate aspect in order to guarantee that the wrapping is filled in an aseptic environment. In fact, if this did not happen, the effects of the previous sterilization step would be nullified.

To ensure this, it is provided that a cup-shaped connection element, also called “false tube” or “false bottle” in the language of the sector, is selectively disposed in flow communication with the line that feeds the product and/or sterilizing agent, so that the feed member always remains inside a closed, sterile zone, at a pressure higher than atmospheric pressure, and delimited by the false bottle in cooperation with the wrapping itself, also in the interval of time between the sterilization step and the filling step.

The teachings of U.S. Pat. No. 5,335,479 and EP 3.643.630 provide that first a cleaning and sanitizing step of the parts to be sterilized is carried out, and—only subsequently—the actual sterilization step. These steps are naturally carried out in succession when the aseptic operating machine is started, before it begins its normal operation to fill the wrappings with the product.

Typically, the cleaning and sanitizing steps are carried out using a cleaning agent, such as alkaline or acid solutions.

The solution described by U.S. Pat. No. 5,335,479 provides a telescopic configuration of the ducts that feed the product, the water vapor first, and then the sterilizing agent, which are delivered one after the other through the same feed line that will subsequently deliver the product.

One disadvantage of this solution is its complexity, which makes it expensive and inconvenient to use. In fact, at the end of the sterilization step the false bottle remains partly confined inside a portion to be discarded of the tube formed by the film, which when it is separated from the wrapping being formed falls downward due to gravity, together with the false bottle. This document therefore describes a technical solution that is not suitable to be integrated into an industrial packaging machine, characterized by high productivity, but rather a solution in which many manual operations are required, managed by the operator, which is in any case inconvenient to put into practice.

Another disadvantage is linked to the fact that—due to its high temperature—the water vapor increases the temperature of the ducts it passes through and of the feed member, so that it is not possible to start packaging until the heat is completely dispersed.

In fact, the circulation of a thermolabile product would inevitably cause it to degrade, with the consequent loss of its characteristics. In some cases, being subjected to heat could also lead to the formation of toxic compounds.

In an attempt to mitigate these disadvantages, the solution described in document EP 3.643.630 provides a feed circuit comprising a first feed line configured to feed the product to be packaged, a second feed line configured to feed a sterilizing solution, and a third feed line configured to feed a gaseous fluid.

The feed lines described above each terminate with a respective dispensing member, for example, the end of a duct, in correspondence with the feed member.

Before the step of forming and filling the wrappings, or before the packaging machine is functioning at normal working speed, it is necessary to clean and sanitize and then sterilize both the first and also the third feed line, respectively of the product and of the gaseous fluid.

In particular, EP 3.643.630 provides to feed the water vapor at a high temperature (about 121° C.) into the feed lines of the gaseous fluid and sterilizing solution, while an acid cleaning solution is fed into the line that feeds the product.

Following the sterilization step a purging step is provided, in which the gaseous fluid is fed into the feed lines of the gaseous fluid and sterilizing solution in order to purge the water vapor, and the product is fed through its feed line to purge the acid solution.

In light of this, this technical solution requires a line to discharge the sterilizing solution and gaseous fluid in order to extract and aspirate them at the end of the sterilization step, thus entailing greater plant complication, and therefore greater manufacturing costs.

Furthermore, in the solution described by EP 3.643.630, the false bottle has to necessarily have two separate environments, one for the discharge of the water vapor, the other for the discharge of the acid solution, since it is characterized by greater structural complexity. Among other things, the false bottle is mobile toward and away from the feed lines, and therefore it is obvious how, during use, the management of the connection element is much more complex, since it has two inlets and two outlets for each of the fluids that flow through it, each provided to ensure the correct circulation of the fluid in a dedicated circuit, separated from the other. In both cases described by the two prior art documents mentioned above, at the end of the sterilization operations, the false bottle has to be disconnected.

In fact, it must be considered that, in order to proceed with the subsequent step of forming and filling the wrapping with the product, the disconnection of the false bottle has to be operationally coordinated with the descent of the film that delimits the sterile environment and that is disposed around the product feed member. The film has to be sterilized again, in order to prevent contaminating the nozzles. This has to be performed while always keeping the product feed member inside the film, without exposing it to ambient air, otherwise the necessary sterile conditions will be lost.

It is therefore obvious that these aspects constitute a considerable disadvantage of the solutions known in the state of the art, all the more significant if one considers that these operations have to be carried out in a short time, at high speed, in order to be able to reach the high productivity of the industrial packaging machines known in the state of the art.

There is therefore a need to perfect a method and a packaging machine for the aseptic filling of wrappings that can overcome at least one of the disadvantages of the state of the art.

In particular, one purpose of the present invention is to provide a method and a packaging machine which allow to speed up the times between a machine stop and the restart of production.

Another purpose of the present invention is to provide a method and a packaging machine which allow to sterilize and fill the wrappings efficiently.

Another purpose of the present invention is to provide a reliable method and packaging machine which guarantee that all parts of the apparatus that come into contact with the film from which the wrapping will be formed are kept in a sterile atmosphere until the wrapping is closed.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

In accordance with the above purposes, there is provided a method to sterilize a packaging machine and a packaging machine which overcome the limits of the state of the art and eliminate the defects present therein.

The sterilization method is to be applied to a packaging machine provided with a feed circuit, configured to feed into wrappings a product by means of a first flow, a sterilizing solution by means of a second flow and a gaseous fluid by means of a third flow, by means of respective feed lines of the feed circuit.

The packaging machine also comprises a forming and filling station equipped with a delivery member fluidically connected to the three feed lines as above, so as to deliver the product, the sterilizing solution and the gaseous fluid. It is provided to form a tubular wrapping of film of heat-sealable material around the delivery member, which will be used to produce the wrappings during the normal production phase of the machine.

According to one aspect of the invention, the start-up step of the packaging machine comprises a sterilization sub-step in which the second flow of sterilizing solution is fed into the first feed line. Preferably, during this sterilization sub-step, the second flow is also fed into the third feed line.

Preferably, the method provides, in the start-up step, a sub-step of forming the tubular wrapping of film of heat-sealable material around the delivery member. The tubular wrapping is closed downstream of the delivery member. More preferably, the sub-step of forming the tubular wrapping occurs before the sterilization sub-step.

Favorably, the machine start-up step comprises a sub-step of sanitizing the product feed circuit, followed by a sub-step of drying the feed circuit. The drying sub-step is preferably carried out by feeding hot air into the feed circuit, in particular into the three feed lines. Both the sanitizing and also the drying sub-steps are performed before the sterilization step. It is preferable to provide that the drying sub-step occurs just before the sterilization step.

The sterilizing solution is preferably a mixture of hydrogen peroxide and air in gaseous form. More precisely, the hydrogen peroxide and air are mixed to produce hydrogen peroxide vapor (HPV).

The above method allows to remove the “false bottle” at the end of the sanitization and to use the film as an insulator of the group of nozzles from the external environment during the HPV sterilization step. In this way, it is no longer necessary to remove any tools at the end of the sterilization, which prevents exposure of the nozzle to recontamination risks. Since the tubular wrapping of film is already formed around the nozzle at the beginning of the sterilization step, once the latter is finished, it is simply necessary to move the film in order to proceed with normal production, maintaining the sterility of the nozzle.

According to one aspect of the invention, a packaging machine is also provided, favorably for packaging a product into wrappings. The packaging machine preferably comprises a first feed line configured to feed a first flow of product from a first source, a second feed line configured to feed a second flow of sterilizing solution from a second source, and a third feed line configured to feed a third flow of gaseous fluid from a third source. It should be noted that the first, second and third sources are comprised in the packaging machine.

The packaging machine also comprises a forming and filling station equipped with a delivery member fluidically connected to the three feed lines and around which it is provided to form a tubular wrapping of packaging film, preferably a film of heat-sealable material.

In accordance with some embodiments, the first feed line is fluidically connected to the second feed line by means of the third feed line. In this way, it is possible to feed the sterilizing solution into the product feed line.

Advantageously, the packaging machine also comprises a closing member connected to the first feed line in the proximity of the first source, more preferably directly downstream of the first source, so as to be able to selectively and fluidically isolate the product source from the product feed line. In this way, it is possible to prevent the outflow of the sterilizing solution into the product source. Preferably, the closing member is of the openable and closable type; being for example configured as a valve.

Favorably, the packaging machine comprises one or more closing members, configured to selectively isolate the third feed line from the first feed line and/or from the second feed line.

According to some embodiments described here, the packaging machine comprises a first connection duct fluidically connected both to the second feed line and also to the third feed line, and a second connection duct fluidically connected both to the third feed line and also to the first feed line.

Advantageously, the first connection duct and the second connection duct are each equipped with a respective closing member, so as to be able to fluidically isolate the three feed lines from each other. Preferably, the closing members are configured as valves.

ILLUSTRATION OF THE DRAWINGS

These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

FIG. 1 is a schematic representation of a feed circuit to feed the product to be packaged, and of operating fluids used in the sterilization method according to the present invention, wherein the circuit is implemented in a packaging machine to carry out a method according to the embodiments described here;

FIGS. 2A, 3A, 4A, 5A and the corresponding FIGS. 2B, 3B, 4B and 5B are schematic sequences showing successive steps of a method in accordance with the teachings of the present invention, in which some parts of the packaging machine according to the present invention are shown.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be combined or incorporated into other embodiments without further clarifications.

DESCRIPTION OF SOME EMBODIMENTS

We will now refer in detail to the possible embodiments of the invention, of which one or more examples are shown in the attached drawings, by way of a non-limiting illustration. The phraseology and terminology used here is also for the purposes of providing non-limiting examples.

The sterilization method can be actuated by a packaging machine indicated as a whole with reference number 10, and operating, for example, according to the feed circuit shown in FIG. 1 , which in turn is indicated with reference number 100.

The feed circuit 100 comprises at least a first feed line 101 connected to a source 15 of the product P, a second feed line 102 connected to a source 14 of sterilizing solution S and a third feed line 103 connected to a source 13 of gaseous fluid A.

The first feed line 101 is configured to feed a first flow F1 of product P, the second feed line 102 is configured to feed a second flow F2 of sterilizing solution S, and the third feed line 103 is configured to feed a third flow F3 of gaseous fluid A. The product P can be a food substance in fluid form such as sauces, juices, or dairy products, or in solid form such as a granular material. The product can also be of a pharmaceutical or cosmetic nature, or of any other nature whatsoever that requires sterile packaging.

The sterilizing solution S can be any substance whatsoever known to have a biostatic or biocidal effect, preferably with a broad spectrum.

Preferably, the sterilizing solution comprises hydrogen peroxide, more preferably it is a mixture of hydrogen peroxide and air to form hydrogen peroxide vapor (HPV).

The gaseous fluid A can be ambient air, in which case the source 13 can be, for example, a blowing device, or compressed air, in which case the source 13 can be a cylinder or a tank. In each case, the gaseous fluid has to be sterile at source or sterilized once introduced into the feed circuit 100 by means of suitable air treatment devices, of a known type and not shown.

The feed circuit 100 terminates in correspondence with a forming and heat-sealing station 12, which in turn comprises a delivery member 120, for example configured as a nozzle indicated by the dashed rectangle in FIG. 1 and schematically also shown in FIG. 2 . The forming and heat-sealing station 12 is configured to receive packaging material, for example a heat-sealable film M, to form the wrappings to be sterilized and filled.

In particular, the heat-sealable film M is fed and wound longitudinally around the delivery member 120 so as to form a tubular wrapping I, closed below the delivery member 120 by suitable welding means, not shown (FIG. 2 ).

The delivery unit 120 comprises a first delivery duct 121 connected to the first feed line 101, a second delivery duct 122 connected to the second feed line 102, and a third delivery duct 123 connected to the third feed line 103.

The delivery ducts 121, 122, 123 of the delivery member 120 are fluidically connected to the respective feed lines 101, 102, 103, so that the product P to be packaged is delivered by means of the first delivery duct 121, the sterilizing solution S is delivered by means of the second delivery duct 122, and the gaseous fluid A is delivered by means of the third delivery duct 123. Each delivery duct 121, 122, 123 has a respective delivery end, obviously open.

The first feed line 101 comprises a duct 31 configured to connect the source 15 of the product P to the first delivery duct 121.

The second feed line 102 comprises a duct 32 configured to connect the source 14 of sterilizing solution S to the second delivery duct 122.

The third feed line 103 comprises a duct 33 configured to connect the source 13 of gaseous fluid A to the third delivery duct 123.

Each duct 31, 32 and 33 comprises a respective valve 21, 22 and 23 configured to control the flow rate of the respective flows toward the feed member 12.

The feed circuit 100 can comprise a duct 34 configured to connect the duct 32 to the duct 33, so as to provide to mix the flows of gaseous fluid A with the sterilizing solution S in order to allow the sterilizing solution S to flow into the third feed line 103.

The duct 33 can also be provided with another valve 24, positioned upstream of the valve 23, with reference to the direction of the flow of gaseous fluid A from the source 13 toward the forming and filling unit 12. The other valve 24 allows to block the flow of gaseous fluid A in the duct 33, or to isolate the source 13 of gaseous fluid. For this purpose, the other valve 24 is preferably also upstream of the connection point between the duct 33 and the duct 34, with reference to the direction of the flow of gaseous fluid A from the source 13 toward the forming and filling unit 12 (FIG. 1 ).

The duct 34 can be provided with a valve 25 so as to selectively allow or prevent the sterilizing solution S from reaching the feed duct 33 of the gaseous fluid A.

The feed circuit 100 can also comprise a duct 35 which connects the third feed line 103 to the first feed line 101. The second feed line 102 can therefore also be connected to the first feed line 101, by means of the ducts 34 and 35.

The duct 35 can be provided with a valve 26 which allows to deflect at least part of the flow circulating in the duct 33 toward the duct 31. The flow circulating in the duct 33 can be a flow of gaseous fluid A or a flow of HPV, as explained above.

The source 15 of the product P can be provided with a valve 27 configured to selectively isolate the source 15 from the rest of the feed circuit 100, for the purposes which will be explained below. According to some embodiments, there can be provided other inputs/outputs associated with the source 15 to introduce service fluids for washing and sterilizing the source into it, or to discharge them from it. With each of these inputs/outputs there can be associated corresponding valves, also not shown, to selectively regulate the flow of fluid.

In this way, it is possible to feed the HPV through all three feed lines 101, 102, 103 so as to perform the sterilization thereof, while keeping the sources 13, 15 of sterile gas A and product P, respectively, isolated. This is particularly advantageous, as well as during the start-up step of the machine 10 (as will be explained below), in the event of a loss of sterility during a production cycle. The measure as above allows to carry out a quick sanitization and sterilization cycle of the circuit 100, which only involves the feed lines 101, 102, 103 and the delivery member 120, thus reducing machine downtime. This is particularly useful in case of loss of sterility in the feed circuit, for example following damage to the film of heat-sealable material.

In some embodiments, the machine 10, as indicated above, can include a control unit 40 to control at least the flow rate of the flows at exit from the sources 13, 14, 15.

The control unit 40 can be connected to flow sensors 43, 44 and 45 configured to measure the flow rate of a flow.

The flow sensor 43 is associated with the feed duct 33 of the gaseous fluid A downstream of the valve 23.

The flow sensor 44 is associated with the feed duct 32 of the HPV sterilant downstream of the valve 22.

The flow sensor 45 is associated with the feed duct 31 of the product P downstream of the valve 21.

It is also possible to provide that the control unit 40 can regulate flows of fluids circulating in the circuit 100 by appropriately commanding the valves 21-27 described above.

To illustrate this concept, in the circuit 100 of FIG. 1 the control unit 40 is operatively connected, in a schematic manner, both to the valves 21-27 and also to the flow sensors 43, 44 and 45 by means of respective dotted lines.

A sterilization method according to the present invention is described below, which can preferably be actuated in a packaging machine provided with the feed circuit 100 shown in FIG. 1 .

The method comprises a step of starting-up the machine, in which the feed circuit 100 is cleaned and sterilized, and which precedes putting the packaging machine in a steady state of production.

In particular, and advantageously, the method provides to form a tubular wrapping I with the film of heat-sealable material M, and to close it both longitudinally and also transversely below the delivery member 120, so that the latter is at least partly contained in the tubular wrapping. In particular, it is desirable that the delivery ends of the three delivery ducts 121, 122, 123 are located inside the tubular wrapping I.

In this way, a sterilization chamber is created delimited by the tubular wrapping I.

The start-up step provides to feed the flow F2 of sterilizing solution into the first feed line 101.

The sterilization of the first feed line 101 by means of HPV allows to not use a false bottle during the sterilization sub-step. Furthermore, the use of HPV replaces the use of water vapor used in the state of the art, allowing to sterilize the first delivery duct 121 as well as the inside of the tubular wrapping I without damaging the film of heat-sealable material M. It should be noted that, in the present sterilization method, the water vapor is not made to flow through the feed lines 101, 102, 103 for their sterilization.

Furthermore, in this way it is possible to produce a machine 10 with fewer components compared to known machines and therefore easier to assemble, maintain and less prone to machine downtime due to the loss of the sterile condition.

According to another aspect of the invention, in the start-up step the second flow F2 is also fed into the third feed line 103 (FIG. 3 ).

FIGS. 2-5 show a sequence of sub-steps that define the start-up step. Since the packaging machine 10 is in the start-up step, all the valves of the circuit 100 are closed, so that no substance circulates in the feed lines.

The start-up step shown provides a cleaning sub-step (FIG. 2A), in which the source 15 of the product P is isolated from the rest of the circuit, and is cleaned by means of a flow of washing liquid, which is preferably made to flow through the circuit 100 (FIG. 2B).

The cleaning sub-step also provides to feed a cleaning fluid, or a washing liquid, such as for example an alkaline or acid solution.

Following the cleaning sub-step, a sub-step of drying the circuit 101 is carried out, not shown, preferably by feeding a flow of hot air through it.

Once the circuit 100 and the delivery member 120 have been dried, the film of heat-sealable material M is fed and wrapped around the delivery member 120, so as to form a tubular wrapping I, which is closed by means of at least one longitudinal weld and one transverse weld below the delivery member 120. A physical separation is thus created between the delivery member 120 and the external environment. One advantage related to this step is that the tubular wrapping I is already formed and ready for production.

Subsequently, a sterilization sub-step is provided, in which it can be provided to make the HPV pass through the first, second and third feed lines 101, 102 and 103 (FIG. 3A). The valve 27 remains closed to isolate the source 15 of the product P from the feed circuit 100. The valve 24 is also closed, in order to prevent the flow of gaseous fluid A into the third line 103, while the valves 25 and 26 are open: in this way, the HPV can circulate at least in the second and first feed lines 102 and 101. It is provided that the HPV can also circulate in the third feed line 103, as schematically shown in FIG. 3A.

In the meantime, water vapor is made to flow into the source 15 in order to provide to its sterilization (FIG. 3B).

Furthermore, it is possible to achieve a sterilization of the feed lines 101 and 103 with a feed circuit 100 of simple construction.

At the end of the sterilization sub-step, the method can provide a purging sub-step in which the third flow F3 of gaseous fluid A is fed into the first and third lines 101, 103 in order to purge the sterilizing solution therefrom (FIG. 4A).

The flow F2 from the source 14 to the feed line 102 can in any case be interrupted to reduce the consumption of sterilizing solution S. In this way, the feed lines 101 and 103 are sterile and suitable to feed in a sterile manner, respectively, the product P and the gaseous fluid A into the tubular wrapping I, at least as long as they are kept in overpressure.

In the purging sub-step, compared to the sterilization step, it is provided to close the valve 25 so as to block the flow of HPV and limit it to the second feed line 102 only, and to reopen the valve 24 so as to allow the gaseous fluid to flow into the third feed line 103. The valve 26 is kept open, so that the gaseous fluid A also circulates in the first feed line 101. In this way, the passage of the gaseous fluid eliminates the residues of HPV and prepares the ducts thus treated for the subsequent production step (FIG. 4A).

At the end of the purging sub-step, each feed line 101, 102, 103 is suitable to make the content of the respective source circulate toward the delivery member 120 and then into the tubular wrapping I of film of heat-sealable material M. In other words, the machine 10 is ready to operate normally.

It is noted that, at this point, the tubular wrapping I of heat-sealable film M has already been created and closed, and it is also sterilized inside. Therefore, there is no longer the delicate step of closing the film, which in known methods involves the risk of compromising the sterilization just performed. Another advantage of the above method is that it also allows to sterilize the outside of the delivery unit 120 enclosed in the tubular wrapping I.

Subsequently, it is therefore possible to proceed with steady state production, disposing the product P in its source 15, and making the product P flow along the first feed line 101, the HPV along the second feed line 102, and the gaseous fluid A along the third feed line 103 (FIG. 5A). Such outflows are allowed by leaving the valves 21, 22 and 23 open.

At the same time, the three feed lines 101, 102, 103 are each isolated from the others, by closing the valves 25 and 26. It is also provided to close at least the valve 27 so as to prevent the exit of product P from the circuit upstream of the first feed line 101, so that the product can only flow downstream, as shown in FIG. 5B.

It is clear that modifications and/or additions of steps may be made to the sterilization method as described heretofore, without departing from the field and scope of the present invention as defined by the claims.

In the following claims, the sole purpose of the references in brackets is to facilitate reading: they must not be considered as restrictive factors with regard to the field of protection claimed in the specific claims. 

1. A method to sterilize a packaging machine provided with a feed circuit, comprising: a first feed line configured to feed a first flow of product, a second feed line configured to feed a second flow of sterilizing solution, and a third feed line configured to feed a third flow of gaseous fluid, and a forming and filling station equipped with a delivery member fluidically connected to said feed lines and around which it is provided to form a tubular wrapping of heat-sealable film, wherein the start-up step comprises a sterilization sub-step in which said second flow of sterilizing solution is fed into said first feed line.
 2. The method as in claim 1, wherein in said sterilization sub-step said second flow (F2) is fed into the third feed line.
 3. The method as in claim 1, and further providing a sub-step of forming the tubular wrapping of heat-sealable film around the delivery member, wherein said tubular wrapping is closed downstream of said delivery member, said sub-step of forming the tubular wrapping being performed before the sterilization sub-step.
 4. The method as in claim 2, comprising, after said sterilization sub-step, a purging sub-step in which said third flow is fed into said first and third feed lines.
 5. The method as in claim 1, and further providing, before the sterilization sub-step, a sub-step of cleaning or sanitizing the feed circuit, followed by a drying sub-step.
 6. A packaging machine for packaging a product in wrappings provided with a feed circuit comprising a first feed line configured to feed a first flow of product from a first source, a second feed line configured to feed a second flow of sterilizing solution from a second source, and a third feed line configured to feed a third flow of gaseous fluid from a third source, and a forming and filling station equipped with a delivery member fluidically connected to said feed lines and around which it is provided to form a tubular wrapping of heat-sealable film, said packaging machine wherein said first feed line is fluidically connected to said second feed line by means of said third feed line.
 7. The packaging machine as in claim 6, comprising at least one closing member disposed on said first feed line downstream of said first source, in the proximity thereof, so as to selectively isolate it from said first feed line.
 8. The packaging machine as in claim 6, comprising one or more other closing members configured to selectively isolate the third feed line from said first feed line and/or from said second feed line.
 9. The packaging machine as in claim 7, comprising a duct fluidically connected both to the second and also to the third feed line in order to reciprocally connect said second and third feed lines, and a duct which fluidically connects said third feed line to the first feed line in order to reciprocally connect said first and third feed lines.
 10. The packaging machine as in claim 9, wherein the ducts each comprise a respective valve so as to be able to isolate each feed line from the other. 